This invention relates to catalytic reactors for the catalytic reaction of SO.sub.2 to SO.sub.3, comprising a plurality of separate reaction chambers, which contain catalyst trays, which are connected in parallel in the gas flow path and consist of catalyst and gas-permeable plates, and gas spaces between the catalyst trays and before the first and behind the last catalyst tray, conduit means for feeding partial streams of SO.sub.2 -containing gases into gas spaces, conduit means for withdrawing the gases from gas spaces when the gases have passed through the catalyst trays, and cooling means for cooling the gases as they flow from one reaction chamber into the next.
In the conventional catalytic reactors, a plurality of catalyst trays are arranged one over the other and SO.sub.2 -containing gases pass therethrough from top to bottom or partly from bottom to top. Gases which have passed through a catalyst tray are cooled to the operating temperature of the next catalyst before they enter the same. For this purpose the gas spaces under and over the catalyst trays are completely separated by partitions or are separated by gas-permeable heat exchangers or mixing plates, in which cooling gases are admixed. In most cases, partitions are provided for a complete separation and the gases are withdrawn from a gas space through a gas outlet pipe and are then cooled in heat exchangers disposed outside the catalytic reactor and supplied through a gas inlet pipe into the other gas space (Printed German Application No. 1,186,837, German Patent Specifications Nos. 1,567,671; 662,445 and 972,117, Printed German Application No. 1,118,164).
Owing to structural and economic consideration, these catalyst vessels are suitable for gas rates up to about 100,000 standard cubic meters per hour. With higher gas rates, the catalyst tray must be so large in diameter to accommodate the required quantity of catalyst that a large number of supports are required. Besides, the pressure loss becomes very high.
It has also been proposed to reduce the overall height of catalytic reactors in that the partitions between the catalyst trays are inclined and the gas outlet and gas inlet pipes on both sides of a partition are offset relative to each other (Printed German Application No. 2,157,198). These proposals do not afford an advantage as far as the accommodation of large quantities of catalyst for high throughput rates is concerned.
It is also known for an operation with high throughput rates to provide in each reaction chamber two catalyst trays, which are arranged one over the other and connected in parallel in the gas flow path. In such arrangements, a partial stream of the SO.sub.2 -containing gas is introduced above the upper catalyst tray and another below the lower catalyst tray, the partial streams are combined when they have passed through the catalyst trays, and the combined streams are withdrawn from the space between the catalyst trays (German Patent Specification No. 1,258,400). That arrangement results in a smaller cross-section and volume of the catalytic reactor and in a lower temperature so that a gas throughput rate up to about 200,000 standard cubic meters per hour is enabled.